Electric throttle engine



Feb. 23,' 1943. c. .1. CRANE Erm.

ELECTRIC THROTTLE ENGINE Filed July 51, 1940 5 Sheets-Sheet l Feb. 23, 1943. c. J. CRANE ETAL ELECTRIC THROTTLE ENGINE 5 Sheecs-Sheet 2 Filed July 3l, 1940 Feb. 2 3, 1943. c. J. CRANE ErAL ELECTRIC THROTTLE ENGINE 5 Sheets-Sheet 3 Filed July 3l, 1940 Feb. 23, 1943. Q 1 CRANE E1-AL 2,311,642

Y l ELECTRIU THROTTLE ENGINE Filed July 3l, 1940 5 Shee'S-Sheet 4 U50/96.6 1./ H fam/04@ W w, N w n m, W WN d. c e a@ t n wm. E Q 8%.... QQQQK .WWQWMY Feb. 23, 19.43. y c. J. CRANE ETAL i ELECTRIC THROTTLE ENGINE Filed July 31, 1940 5 Sheets-Sheet 5 ooo@ ooooooooo @lfm 4.. 7'0 /Z VOLT C. '50i/ECE Patented Feb. 23, 1943 ELECTRIC THROTTLE ENGINE Carl J. Crane, George V. Hollomamand Raymond K. Stout, Dayton, Ohio Application July 31, 1940, Serial No. 348,720

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 12 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to a control system for regulating the flight conditions of an aircraft in a vertical plane such as rate of climb, rate of descent and constant airspeed at a particular altitude by regulation of the output of the power plant, and more particularly relates to a novel electric servomotor device of the ltype commonly known in the art as a throttle engine, for auto-l matically setting the aircraft engine throttle in certain predetermined positions and for making a vernier, or as hereinafter termed a micrometric adjustment of the engine throttle about one or more of the predetermined throttle positions in accordance with variation in flight conditionsof the aircraft, such conditions being, for example, variation in the rate of climb or descent of the aircraft from a predetermined value, variation in the horsepower output of the engine, measured, for example, by change. in the intake manifold pressure or by variation in the velocity of the aircraft from a predetermined value, measured, for example, by a Venturi tube.

Devices of the type described have a general ultlity in replacing the conventional manual throttle control, but in particular have been found to be practically a necessity in carrying out automatic instrument landings in accordance with an improved form of the Army Air Corps blind landing system, fully disclosed in application Serial No. 287,310, filed July 29, 1939, entitled Aircraft- Automatic take-off flight and landing, in the names of Carl J. Crane, George V. Hollom'an, Raymond K. Stout, and Constantin D. Barbulesco.

The device according to the invention comprises an electric motor connected through a clutch to drive a shaft which through suitable linkage actuates the engine throttle valve. The motor-driven shaft also actuates a series of cams which control contact switches, which in turn respectively control the motor-energizing circuit and selectively serve to deenergize the electric motor in predetermined throttle positions. The predetermined throttle positions are selected by closing a switch associated with a respective camaotuated switch. A servomotor of the type described is not new per se, being of a type used in the remote tuning of a radio set, as evidenced by United States Patent No. 2,955,363 granted to Winfred T. Powell. A novel feataure ci the device, in accordance with the invention, however, ls the provision of a means to mlcrometrically adjust the throttle about one or more of the predetermined throttle settings, the mlcrometric adjustment being effected by shifting the camactuated contact switch assembly associated with a particular cam, relative to the cam by an electric motor controlled by a rate-of-climb-responsive means, an engine intake manifold-pressureresponsive means, or by a means responsive to variation in the air speed of the associated alrcraft. By means of these automatic mlcrometrlc adjustment features, the air speed of the aircraft may be kept at a substantially constant value during an approach to the landing eld and, during the glide for va landing, may be kept descending at a constant rate as determined by the rate-of-climb-responsive means, which, of

course, is understood in the art to include rate of climb or descent.

A further novel feature of the invention is the provision of a means for setting the cams in positions corresponding to the desired engine speeds during flight, the setting means being controlled from a point remote from the throttle engine. The novel setting means permits the throttle engine to be placed in the engine compartment adjacent the engine throttle valve and the cams Vling throttle in any one o a plurality of prede-s termed positions and to micrometricaliy adjust the throttle about at least one of said predetermined positions.

A further object or" the invention is the provision in a device oi the character described, of a means to selectively control the micrometric lmeans in accordance with a condition of aircraft night, such a condition being engine power variation, variation in vertical velocity of the aircraft, or variation in the air speed of the associated aircraft.

A further object of the invention is the provision of an electric servomotor for controlling craft;

an aircraft engine throttle, or the control surface of an aircraft, of a type such that it may be operated to place the engine throttle, or the control surface, in any one of a plurality of predetermined positions, and in one of said positions to be lalways returned to the said one position after any displacement due to sudden jars or shocks. l

Other objects of the invention not specically enumerated above will become apparent to those skilled in the art by reference to the specification and the appended drawings, in which:

Figure 1 is a side elevation showing the association of the electric throttle engine with the motor of an aircraft;

Figure 2 is a front elevation engine;

Figure 3 is a view partly in section taken on line 3-3 ofFigure 2;

Figure 4 is a schematic diagram showing the electrical circuit arrangement;

Figure 5 is a schematic view illustrating the operation of the cam control of the servomotor;

Figure 6 illustrates a modified arrangement of a portion of the device of Figure 4, to be responsive to variation in velocity of the associated aircf the throtue Figure 7 is a diagrammatic showing of a modiiied.` form of throttleengine having a self-locking' feature.

Referring to Figure 1, the reference numeral I represents a conventional aircraft engine having an intake manifold 2, provided with a carburetor 3, having a conventional,throttle-controlling element 4. The throttle-controlling element 4 is pivotally connected to a lever 5 which is centrally pivoted on a floating lever 6, which is connected at its lower end to a manual control rod 'I, actuated by a manual throttle control 8. At its upper end, the fioating lever 6 is pivotally connected to one end of a lever 9, which is pivotally connected at its other end to an arm I8 fixed on a shaft II of an electric throttle engine, generally indicated by the reference numeral I2. The

throttle engine I2 is adapted to be energized by aircraft storage battery 40 and is also operatively connected to a -rate-of-climb-responsive device 1I, a switch panel-generally indicated by the reference numeral |00, and an intake manifold pressure conduit 85, all of which function in a manner hereinafter to be more particularly described. It will be seen that the throttle-control element 4 may be manually actuated by means of the throttle control 8, or may be automatically actuated by the throttle engine-I2. When it is desired to utilize the automatic control, the throttle control arm 8 is moved to the closed position, and the throttle engine, through link 9 and pivoted lever 6, may then actuate the throttlecontrol element 4 independently of the manual control lever 8.

elements I8 and I9, upon the magnetic solenoid 22 being energized and/or de-energized, respecducing gear 28 which, in turny is driven by theA armature shaft'29 of a reversible direct current motor 30. It will thus be seen that the motor 3D may drive the throttle engine shaft I I in either direction, upon the clutch elements I8 and I 9 being engaged, thus causing the arm I8 to actuate the throttle element 4 of Figure 1, as hereinbefore described with reference toFigure 1. A plurality of cams C1, C2, C3, C4, and C5, are respectively frictionally mounted on the shaft II between the vertical supports I3 and I4. Each of these cams is respectively adapted to cooperate with a spring contact member 44a, 44h, 44e, 44d, and 44e. Each of the contact arms 44a, etc., is provided with a cam follower 45 which is yieldingly urged into contact with its associated cam. Each 'respective cam is provided at its central Aportion with an enlarged hub 48 having a bushing 49 of rubber, or other suitable friction material, keyed therein. The friction bushing 49 .serves to maintain each respective cam in a fixed angular relation with respect to the shaft II, but permits the cams to be angularly adjusted with respect to the shaft II in a manner hereinafter more particularly described. Each cam is provided with 'a raised arcuate section 50 and a depressed arcuate section 5I, the two arcuate sections being joined by a sloping section having a neutral point 52 midway 'between the sections 5I) and 5I. Each of -the flexible Contact arms 44a, 44b, etc., has mounted thereon adjacent the outer end, a double contact 46 which` is adapted to contact either a front contact 4'I or a rear contact 48 associated therewith. It'will be seen by inspection of Figure 3 that when, for example ca'm C1 is rotated so as to bring the raised arcuate cam section 50 into contact with the follower Referring now' to Figures 2 and 3, the construction of the throttle engine I2 will now be described. The throttle engine I2, comprises a base I5 having vertical supports I3 and I4 mounted thereon, which supports serve as journals for a shaft I I having the arm I0 secured at the outer end thereof. At its inner end the shaft I I is prol 45, Contact 46 will engage the front contact 41 associated therewith; whilel if the cam follower 45 engages the depressed cam section 5I, the yielding contact strip 44 will urge the contact 46 into engagement with the rear Contact 48. When the cam follower 45 engages the neutral cam section 52, the double contact 46 will then be spaced midway between the contacts 41 and 48 and out of engagement with either of these contacts. The spring contact members 44a, 44D, and 44e, respectively, are mounted on a block of insulating material 54 secured by a suitable stationary mounting to the vertical support I3. The front and rear contacts 47 and 48, respectively, which cooperate with the respective cams C1, C2, and C3, are each supported on an insulated block 55, also suitably supported by the vertical support I3. The flexible contact members 44d and 44e are each mounted adjacent their lower ends onl a `block 56 of insulating material carried by an arm 51 secured to a hub member 58 which is freely rotatablyl mounted on the shaft ii. The front and rear contact members 4'! and 48, which cooperate with cams C4 and C5, are each carried by an insulating member 6I similar to the member 55, but the insulating member 6I is mounted on an arm 60 which is also secured to the hub member 58. It will be seen that as the hub member 58 is rotated about the axis of the shaft II, contact strips 44d and 44e, and their associated cam followers 45 and contacts 4l and 48 will also be rotated about the axis of shaft II. The

hub member 58 is in frictional engagement with' the side face of a worm gear 59, also freely rotatably mounted on the shaft I l The worm gear 59 is adapted to be driven by a worm 62 mounted on the end ofa shaft 63, which is driven by a speed-reducing gear 64 from the armature shaft 65 of a reversible direct current motor. It is thus seen that motor 66 may rotate the contact assembly associated with the cams C4 and C5 about the axis of shaft Il in either direction of rotation.

As seen in Figure 3, the cams C1, C2, etc., are each provided with a slot 80 which is located diametrically opposite the neutral point 52 on each cam. A solenoid coil 82a,' 8211, etc., is associated with each respective cam. The solenoid coils are provided with a p1unger.83 which is formed of a nonferrous metal, such as brass or aluminum, and threaded into a soft iron plunger 83 which is surrounded by the solenoid windings. The plunger 83' is loaded by means of a spring 84. Whenever a respective solenoid coil 82a, B2b, etc., is energized, the plunger portion 83 engages its associated cam and eventually will enterthe slot l upon rotation of the associated cam and lock the cam in a position such that the cam follower 45 is in contact with the cam at the neutral portion 52, with the double contact 46 out of engagement with either of contacts 41 and 48.

The operating circuit for the throttle engine is illustrated in Figure 4 and, referring to this figure, it is seenthat the driving motor 30`is provided with a. split field having a reverse winding 3l and a forward Winding 32. The forward winding 32 is connected by means of a conductor 34 in parallel with each of the back contacts 48 associated with the respective cams C1, Cz, Cs, C4, and C5. The reverse winding 3l is connected by means of a conductor 33 with the forward contacts 41, respectively associated with the responsive cams C1, C2, C3, C4; and C5. The clutchactuating solenoid 22 is of the double winding type, having one winding connected to the conductor 34 by means of a conductor 24 and having the other winding connected tothe conductor 33 by means of a lead 25. The third lead 23 connects each of the double windings of the solenoid 22 to the negative terminal of a battery 40. The positive terminal of the battery is connected, by a conductor 38, in parallel with each of a series of switches 42a, 42h, 42e, 42d, and 42e, each respectively connected by means of leads 43a, 43h, 43e, 43d, and 43e with the flexible contact members 44a, 44h, etc. It will thus be seen that upon closing any one of the switches 42a, 42h, etc., andv having the double contact 46 of a respective cam in contact with either the front -contact 4101' the rear contact 48 associated therewith, an electrical circuit will be established connecting the clutch-actuated solenoid 22 and either the forward or reverse field winding of the motor 3@ with the battery 43, the armature of the motor 38 being connected to the negative terminal of the battery 4B by means of the conductor 23, 'A switch 3'! also connected to the conductor 38 is adapted to cooperate withl a pair of contacts 35 and 33 to manually connect either the reverse winding 3l or the forward winding 32 of the motor 33 directly with the battery 43 for a cam-setting operation hereinafter described.

The solenoid coils 32a, 32h, 82e, ete., are each connected in series with a respective switch 88a, 88h, 88e, etc., which switches are connected in parallel with the conductor 33. The other terminals of the respeciive solenoid coils 82a, B2b,-

veach respective can to the shaft Il,

82e, etc., are each connected in parallel to the conductor 23. It is thus seen that upon closing any one of the switches 88a, 88h, etc., the respective solenoid coil 82a, 82h, etc., will be energized, causing the associated plunger 83 to lock its respectlve cam C1, C, etc. By energizing a. respective solenoid and simultaneously causing the motor 30 to be rotated in either the forward or reverse direction by actuating switch 3l in the proper sense, the cam can finally be brought to a position such that the associated solenoid plunger 83 will lock the cam. The motor 30 can then be continued in operation until the throttle setting shaft Il has moved to a position which will set the engine throttle at a desired point corresponding to one yof the previously noted flight conditions. This adjustment can be made because of the'frietion connection 49 of previously described, which allows the shaft Il to be driven while a cam is held locked. By means of this operation, each respective cam may be so set that the neutral point 52 (see Figure 3) will be opposite the corresponding cam follower 45, leaving the associated double contact 46 in the neutral position out of engagement with either contact 41 or 48. The solenoid switches 88a, 88h, 88e, etc., are adapted to be mounted on the panel |00 at a point remote from the position of the throttle engine I2, and yet permitting the cams to -be set in the proper position during actual flight of the airplane.

As previously described with` reference to Figures 2 and 3 it is noted that the reversible motor 66 is adapted to rotate the contact assembly associated' with the cams C4, and C5 about the axis of the shaft Il. This rotation of the contact assembly is hereinafter termed a micrometric adjustment, since actual rotation of the contacts is intended to be only a very small amount. The motor 66 is provided with a split field winding having the coils 61 and l2, respectively. The winding 61 is connected by means of a lead 68 to a conductor 69 which, in turn, is connected to a contact TB carried by a movable contact carrier 18 associated with a rate-ofclimb-responsive device 1I. The other field Winding 'l2 of the motor 66 is connected by means of a conductor 14 to a second contact 15 also carried by the Contact carrier '18. The armature of motor 66 is connected to the negative terminal of the battery 40 through the medium of oonducv tor 33. The rate-of-climb-responsive device 'Il is provided with a pointer 73 which carries double contact l?, arranged between the contacts 'I5 and 78 and is adapted to remain in a neutral position out of engagement by a predetermined small clearance with either of the contacts 'iii or l5, upon a predetermined value of rate of climb, or descent being maintained. The pointer it is electrically connected by means oi a conductor 'i8 to the contact of the switch When the switch 42a is closed, it is thus seen that an electrical circuit may be established from battery through conductor 33 and switch 42e, to conductor i3, pointer '16, double contact either of contacts 'l0 or i5, and either of eld coils 6l' or 'l2 through the armature of motor 3S and conductcr 23 to battery 33 to thereby energize the motor SES. The motor 66 then shifts the contact strip 44e and its associated cam follower 43 rel ative to cam C5, so that the cam follower engages one of cam sections 58 or 5i, thus causing contact 45 to engage one of. contacts or to thereby energize the clutch actuating solenoid` -The conductors 14 and 69 are also connected in parallel to a pair of contacts 19 and 80, respectively, carried by a support 8l associated with a manifold-pressure-responsive means. The contact carrier 8l is adapted to be actually shifted by means of a threaded rod and thumb screw, as shown in Figure 4, against the resistance of a coil spring 85 connected at one end thereto and having its other end connected lto a pressure-responsive bellows 84. The bellows 84 is adapted to be connected by means of a conduit 86 to the intake manifold 2 of the engine I, as previously noted with respect to Figure 1. Thebellows SII carries a contact support 82 upon which is mounted a double contact 83 spaced between and adapted to engage either of the contacts 19 or 80, and the double contact 83 is electrically connected byl means of a conductor 81 to the contact of switch 42d. The tension of spring 85 is so adjusted that the contact 83 is normally out of engagement with either contact l19 or contact 80, upon a predetermined manifold pressure representing a desired engine horsepower output being obtained. Upon closure of switch 42d, if the engine horsepower should vary due to night load conditions, the contact 83 can engage either contact 19 or contact 80, to cause the motor 66 to make a micrometric adjustment of the contact assembly associated with cam C4 to cause motor 30 to actuate the throttle adjusting shaft II to restore the engine power output to a value suiicient to carry the new load and thus maintain the engine manifold pressure substantially constant. The operation of the motor 66 is the same as previously described with reference to the rate of climb responsive control.

OPERATION Cam .setting As described above with reference to Figure 4, it is seen that the respective cams C1, C2, C3, etc., can be set in a desired angular relation with respect to shaft I I, corresponding to desired engine throttle positions. Each of the cams C1, C2, Ca, C4, and C5 correspond to certain predetermined engine power output conditions, such as, for example, throttle-off condition, take-oir condition, cruising condition, slow cruising condition, and gliding condition. The cams C1, C2, etc., are set so that-their neutral positions correspond to the associated with the selected switch 88a, etc., will cause the selected cam to be locked as previously described and the motor 38 is continued to be manually operated until the engine throttle is in the desired position, at which time switch 31 is then opened stopping operation of motor 30. The selected cam will then be in a position such that its neutral point 52 will be opposite the corresponding follower 45 and the corresponding contact 46 will be out of engagement with its corresponding associated contacts 41 and 48. The selected locking solenoid switch 88a, etc. is then opened and is not thereafter employed until a resetting is required. Each of the cams is set in a similar manner and after being properly set thereafter serves to control the servomotor 30, so that the servomotor always adjusts the engine throttle to the predetermined position determined in the setting operation. This remote control for setting the respective throttle-controlling cams is deemed a novel feature of the invention, since it is substantially impossible to make the proper adjustment of a number of the cams on the ground, and manual adjustment of partment, which in most aircraft is not accessible A during flight.

-Ser'uomotor operation The operation of the electric servomotor for setting the throttle shaft I I of the throttle engine I2 in any one of its predetermined positions is best understood by reference to the schematic diagram illustrated in Figure 5. As seen in Figits associated cam. If then any one of the switches 42a, 42h, etc., be closed, a circuit will be established from battery 40 to the respective switch, for example, 42a, double contact 46, front contact 41, conductor 33, reverse winding 3| of i, motor 30 through the armature winding thereof requisite throttle positions for each of the above to conductor 23 and to the negative terminal of the battery 40. Simultaneously, a circuit will be completed from the battery 4I) through conductor 33, conductor 25, through one of the windings of the clutch-actuating solenoid 22, to cause the clutch elements I8 and I9 to be drivingly engaged. The motor 30 may then rotate in a direction such as to rotate the cam C1 asindicated by the .arrow in Figure 5. The throttle shaft II will then rotate in the throttle-closing direction until the neutral point 52 of the cam C1 is directly opposite the cam follower 45, at which time engagement between double contact 46 and front contact 41 will be broken. Interruption of this contact will de-energize conductor 33 causing motor 30 and clutch-actuating solenoid 22 to y motor 30 and the shaft 20. The throttle will then be in the oif or closed position. If, for

example, the switch 42e should now be closed and switch 42a opened, the double contact 46 of the contact member 44c will be in engagement with its associated contact 48, causing a circuit to be established from battery 40, conductor 38, switch 42e, contacts 4B and 48 to conductor 34 and the forward winding 32 of motor 39, causing motor 3B to be operated in the direction as indicated by the arrow in Figure 5, to cause the shaft I I to move the throttle-control arm il) in the.

opening direction. The shaft il will continue to open the engine throttle until the engine speed is at a value corresponding to the desired cruising engine speed, at which time the follower 45 will be opposite the neutral point of the cam Cs, interrupting the supply of energy to motor 30 and clutch actuator 22, which is now receiving power through the conductor 24. The .shaft ii will thus ybe de-clutched from driving relation with the motor 30. In a similar manner, by closing any one of the switches 42a, 42h, 42o, etc., the shaft Il c-an be set in any one of the predetermined throttle-setting positions for which each respective cam has been previously set. Any number of cams more or less than the five here illustrated may be used. The structure and operation of the servomotor per se is old in the prior art, as evidenced by the previously noted patent to Powell, and the novel feature of micrometric adjustment will now be described:

Micrometrie adjustment and throttle-control arm i9 in a position veryl closely approximating the desired value, slight Variations d-ue to external conditions ofk ilight` may prevent the actual desired night speed from being actually attained,which would thus require an additional manual adjustment of the throttle, destroying much of the utility of the throttle engine. In order to overcome this difficulty and to obviate the necessity of making manual adjustments, the micrometric adjustment of the throttle shaft ii previously described is employed. if we consider that the shaft ii and associated cam C@ are in the position corresponding to the desired slow cruising night condition switch 2d will be closed, the double contact fifi associated with the cam C. will be out of engagement with either of its associated contacts fl? and and motor it@ and clutch-actuating solenoid will both be deenergized. Ii, however, the velocity of the airplane is at some value other than the predetermined value, the engine horsepower output will vary from the predetermined horsepower output as measured bythe predetermined intake manifold pressure. Any variation in the intake manifoldV pressure from the predetermined value will cause the contact 83 to engage either contact i9 or contact 8d to energize the motor d6 in the manner previously described, Motor Sii will then rotate in a direction such that worm Awill rotate worm gear 59 to frictionally drive the hub 58 and the contact-carrying arms 5l and Eil (Fig. 2) to cause the cam follower 55 associated with the cam C4 to be shifted off the neutral position 52 of the cam. The shifting of the follower 45 will cause the contacts 48 to engage either contact 41 or Contact 48 to energize the clutch-actuating solenoid 22 and motor 30 to effect a throttlc-adjusting rotation of shaft H of such a value as to restore intake manifold pressure to the predetermined value, thus interrupting engagement between contact 83 and one of contacts I9 or 80', to thereby de-energize motor 66 and prevent further adjustment of the cam follower associated with the cam C4. It is to be understood that the motor 65 is so geared to gear 59 that the gear 5S will rotate at a very slow speed, thus giving ample time for engine conditions to be restored to the proper value before any' appreciable adjustment of the contact arms 51 and 6G has been made. However, -in the event of motor 66 making a large adjustment, stops S on the contact carrier 5l (see Fig. 3) will prevent further adjustment of 'the contacts, and the frictional drive between the hub 58 and the gear 5S will permit the gear to slip relative to the hub without stalling motor 66 Y f'ter a descent is started during a blind landing inaccordance with the above-noted system, it

is necessary that a predetermined rate of descent be adhered to, which heretofore required a close manual adjustment of the throttle during the course of the descent. In order to alleviate the necessity for manual adjustment during the glide, the throttle may be rst set approximately in the proper position for a glide by closing the switch 42e, causing cam C5 to effect a setting of shaft i l in the throttle position corresponding to the glide condition. If, howeventhe rate of descent of the airplane should vary'from the .predetermined desired value, the rate-of-climbresponsive device ll may also eifect a micrometric adjustment of the throttle shaft il in the manner previously described with reference to Figure 4. It is seen that the rate-of-climbresponsive mechanism is operative to effect the energization of motor 6E only when the switch .42e is closed, and since only one of the switches 42a to 42e, inclusive, are ever closed at any one time, the possibility of the pressure-responsive device Sii and the rate-of-climb device 'Il being operative simultaneously is thus eliminated. It is thus seen that by means of the above described device, the electric throttle engine may, by actuation of a selected one of the switches 42a, 42o, etc., position the throttle control element G (Fig. l) of the engine i in any one of a plurality of predetermined positions corresponding to denite flight conditions and that in at least two of the selected positions, inicroinetric adjustment or" thethrottle may he obtained to maintain the ight conditions within desired narrow limits Without requiring any manual controlen the part of the pilot. The switches LiZa, Alh, fiile, etc., may be manually actuated by the pilot and mounted on the panel i853' (Fig. i) or one or more of these switchesfor example, switches 42d and L52e-- may be actuated by lautomatic devices, for example, a marker beacon radio receiver. A switch d20: may be, if desired, actuated by a landing gear switch. rShis application, however, is not concerned with the manner in which the various throttle engine switches are actuated, and the means for actuating these switches forms no part of the present invention.

In the device illustrated in Figures l and 4, an engine intake manifold-pressure-responsive device has been disclosed for the purpose of micrometrically adjusting the lthrottle'during the glide flight condition controlled by the cam C5. If desired, however, this device may be actuated by a means responsive to variation in aircraftvelocity from apredetermined value, as illustrated in Figure 6. As seen in Figure 6, the pressure-responsive device 84 is actuated by means of the conduit 86 connected to the constricted throat of a Venturi tube 90 which is adapted to be exposed to the air stream external of the aircaft. The connections of the velocity-responsive device in the circuit of Figure 4 are identical to those already illustrated in Figure 4, so that the same reference numerals have been applied. It is necessary only to replace the spring 85 of the device of Figure 4 by a spring 85 so calibrated and ten- -sioned that the suction' created at a predetermined aircraft velocity in the throat of the Venturi tube 90 will cause the bellows 84 to just balance the load of the spring 85'. If the aircraft velocity should decrease below the predetermined value for the slow cruising condition, the suction produced by the venturi in the bellows 84 will decrease and spring 85 will contract, moving contact 83 into engagement with contact 19, thus energizing the motor 66 through the field coil 6' to operate motor 66 in such a direction as to cause a shifting of the contact follower 45 associated with the cam C4, to cause the shaft to move in the throttle-opening position. If the velocity of the aircraft should increase above the predetermined value corresponding to the slow cruising condition established by cam C4, the suction produced in bellows 84 will increase, causing contact 83 to move downward into engagement with contact 80, causing motor 66, through the field coil 12, to be energized to cause a movement of the contacts and contact follower associated with earn- C, to effect a micrometric adjustment of shaft II', to decrease the throttle setting, to thereby restore the airplane velocity to its predetermined value.

Each of the devices 1| and 84 is. an example only for purposes of illustration and is not to be considered as actual embodiments of devices found most suitable for the intended purpose.

The construction of a rate-of-climb-responsive switch and mechanism or anintake manifoldpressure-responsive switching device per se forms no part of the present invention, since other devices than those illustrated are equally well adapted for the purpose disclosed.

Figure 7 illustrates a modified form-'of throttle engine for controlling the throttle element 4 in a manner similar to the device of Figure 1. In this figure, parts similar to the device of Figures 1 to 5 inclusive are given the same reference numerals, except that the numerals are primed. The device as illustrated in Figure 7 comprises an electric servomotor I I0 havingy a field winding II I and an armature ||2 which is adapted to drive a shaft ||3 in either a forward or reverse direction, depending upon the arangement of the circuit of motor ||0. The shaft ||3 is provided with threads ||4 arranged to form an elongated screw upon which is threaded a nut member I I5 internally threaded as at H6. The nut ||5 is connected by means of a link to the upper end of a floating lever ||8.' The floating lever is pivotally mounted on a stationary pivot ||9 at its lower end. The oating lever I8 is connected to the engine throttle-control element 4 by means of a link |20. Intermediate its ends, the floating lever ||8 is connected by means of a follow-up link |2| to a contact-supporting member |22 made of any suitable insulatingmaterial. The contact-supporting member |22 is supported, by

.gized.

sition of the engine throttle, the second pair.|32,

|33 corresponding to the glide position of the engine throttle, and the third pair "|40, |4| corresponding to the throttle-off position of the throttle-controlling element 4. The slidable contact members |25 and |26 are arranged diagonal-l ly on opposite sides of the contact-supporting member |22 and are electrically connected, and

the slidable contacts |23 and |24 are similarly arranged and also electrically connected. `The pairs of brushes |30, |3| and |40, |4| are arranged to be stationarily supported by a suitable means (not shown). The brushes |32 and |33, however, are mounted on an insulated carrier |34 having rack teeth |35 cut on the external surface thereof and adapted to mesh with a worm |36 mounted on a shaft |31 adapted to be driven by a speed-reduction gear |38, which in vturn is driven in either direction by the motor 66', for the purpose of making a micrometric adjustment similar to the device disclosed in Figures 1 to 5 inclusive. The pinion gear |36 is adapted to cause an axial movement of the contacts |32 and |33 relative to the contact-supporting member |22. 'I'he contact member |26 is adapted to be connected by means of a. fiexible connection (not shown) to a positive power supply conductor |44, and the contact |24 is similarly connected to a negative power supply conductor |45. The power supply conductor |44 has .a switch |46 inserted in series therewith and adapted to interrupt the supply of power when desired. The eld of the motor ||0 is permanently connected across the power supply conductors |44 and |45 by means of the conductors |48 and |49, so that the motor field is continuously energized as long as power is flowing in conductors |44 and |45. A circuit-controlling relay, generally indicated by the reference numeral |50, as shown by the dotted lines in Figure '7, is provided with an actuating solenoid coil |5|, which is adapted to cooperate with each of three relay arms |52, |58 and |64, respectively. The relay arms are each normally biased by means of springs or the like, and attracted downward whenever the solenoid coil |5| is energized.' The relay arm |52 is connected to the power supply conductor |44 by means of a conductor |56, and is adapted, when actuated by the relay solenoid, to engage in contact |53, which is actuated by means of a conductor |54 to one end of the solenoid coil |5| and from thence through a switch |55 to the conductor |56. The other end of the solenoid coil |5| is connected by means of a conductor |51 to the negative power supply conductor |45. It will be seen that whenever switch |55 is closed, the relay coil |5| will be energized, and that upon the relay arm |52 engaging contact |53, the relay coil |5| will be energized through a circuit independent of switch |55, which serves in a holding or locking function in a manner more'particularly hereinafter described. The relay contact arm |58 is adapted, when in its normal position, to engage a contact |59, and to engage an oppositely spaced contact |60 whenever the relay coil |5| is ener- The relay arm |64 is similarly adapted to `engage a contact |61 in its normal -position and to engage a contact |65 when depressed by means of the coil The relay arm I 58 is electrically connected by means of a conductor |62 to one side of the armature I|2 of motor |I0, andv a conductor |63 similarly connects the other side of the armature ||2 to the relay arm |64. The lower relay contact |60, associated with the relay arm |56, is connected by means of a conductor |6| to the brush |40. The lower contact |65, associated with the relay arm |64, is similarly connected by means of a conductor |66 to the brush |4|.

The second circuit-controlling relay, generally indicated by the refrence numeral |10, comprises a solenoid coil |1| connected at one end to the conductor |56 through the medium of a series switch |90, the other end of the solenoid coil |1| being connected to the conductor |61. It will be seen, by inspection of Figure 7, that the solenoid coil |1| is arranged in parallel with the solenoid coil |5|, and can be energized at will by` closing switch |90. The solenoid coil |1| is associated therewith to relay arms |12 and |18 respectively, each of which is adapted to be nor'- mally urged by a spring in one direction to engage upper contacts I14 and |82, respectively. Upon the solenoid coil |1| being energized, the relay arms are respectively drawn downward into engagement with the contacts |16 and |84, respectively. The upper contact |14 is connected by a conductor |15 to the brush |30; and the tively, connected to contacts 15 and 10', respectively, of a rate-of-climb-responsive device 1I', similar to the device 1| of Figure 4. The rateof-climb-responsive pointer 16', having the contact 11 adapted to engage either contact 10' or 15' in the manner previously described with respect to the device cf Figures l to 5, is electrically connected by means of a conductor 13 to one end of the relay solenoid coil 21|. The armature of the motor 66' is electrically connected by means of the conductor |12 to the other terminal of the solenoid |15 of the relay liti. It will be seen by inspection of Figure 1 that whenever the relay coll iii of the relay 51S is energized, the rateof-climb-responsive device i i is adapted to cause operation oi' the motor S6 in the same manner as in the device Figures to 5 inclusive, the actuation of the motor 66" causing a rniciornetric adjus'tment of the brushes and i323, respectively.

i Genimrron The device disclosed in Figure '1 is intended to operate to move the engine-throttle-control element (Figure 4) into the cruising and glide" and throttle-ofijpositions, the first of which will new be described.

In order to cause the enginethrottlecontrol element ai to be placed in cruising position, from the position as seen in Fig. '7, switches 55 and iet are each open, and switch |46 is closed; and power from the positive power supply conduetor |44 will then ilow throughcontact |26 to contact |25, brush |30, conductor |15, contact rent is continuously ilowing through the field coilv i I of motor |0, the motor will begin to run in a direction such that nut I I5 will be fed axially to- 'wards the right,.as seen in Figure 7, opening the engine throttle, and through the medium of the floating link I |8, will cause a simultaneous movement in the same direction of follow-up link I2| in the switch assembly |22 to |26, inclusive. This movement will continue until the dead spaces |28 come opposite the brushes |30 and |3|, thus interrupting the electrical circuit through the motor armature and stopping the motor ||0 and leaving the throttle-control element 4 in an adjusted position corresponding to the desired cruising power output of the associated engine. It will be noted that if, for any reason, the throttle should be jarred beyond the cruising setting, the brushes |30 and |3I would then cony tact the slidable contacts |24 and |26, respectively,which will reverse the flow of current through the motor armature I|2 from that described above, which reversal of current will cause motor ||0 to again restore the throttle to the cruising position. From the above description, it is apparent that whenever the switches |55 and E10-are in the open position, upon closure of the power switch |46 the motor ||0 will always place the enginethrottlecontrol element 4 in the cruising position.

Operation of the servomotor to place the engine throttle element 4 from the "cruising into the glide" position will now be described. In order to effect this throttle setting, the switch is closed-to thereby effect the energizing of the solenoid coil E'H of relay |10-either manually or automatically in response, for example, to a radio signal receiving device, as noted with respect to the device of Figures l to 5 inclusive. Switch |46 being closed, power will be supplied from conductor |44 to Contact i26 then through brush |36, conductor |85, contact |64, and arm Q18 or" relay |16 which is now active. From relay arm |16 the current ows to conductor |18, contact |61, relay arm ld, and conductor 63 to the armature of motor lill. The current returns from armature il? through conductor |62 to relay and contact l and thence by conductor to relay arm i12 and relay contact H6 ci relay llt?. The current then iiows by means of conductor 11 to brush itil and contact i2@ to the negative return line M5 of the power supply, thus completing the circuit. rlhe motor iii] will then. be energized to move the throttle closed until it reaches the predetermined glide position, simultaneously moving the inr sulating support i122 axially to the left until the dead spaces |28 are opposite brushes |32 and |34 as shown in Fig, "I, thereby opening the armature circuit to motor i i6, die-energizing the same. The rate-of-cliinb-responsive device 1i', having been set for a predetermined rate of descent, will control the motor 66' to effect a micrometric adjustment of the brushes |32 and E33 -in the event that the preselected adjustment of throttle 4 is not of lsuch a value as to maintain fe'ct an instrument landing. This micrometrlc adjustment is substantially the same as the micrometric adjustment of the device illustrated in .Figure 4 in the glide position. It is obvious,

h owever, that the Vernier adjustment of the respective brushes could be effected by means of a so desired. It will be noted that regardless of the position of the brushes |32 and |33 relative to the contact assembly |22 to |26 inclusive, the current ow through the armature of the motor ||2 will always be in such a direction that the motor H will adjust .the throttle-controlling element 4 ina position such that the neutral dead spaces |28 will be opposite brushes |32 and |33 for the glide condition.

'I'he throttle-off setting of throttle-control element 4 in Figure 7 from the glide position will now be described: In order to effect the setting of the throttle-control element] of the device of Figure 7 in the off position, the switch |46 will be closed, and switch |55-which preferably is operated automatically by the landing gear upon contact of the aircraft with the groundwill be closed, thus energizing the solenoid coil |5| of the relay |50 in the manner previously described. The relay arm |52 of the relay |50 will engage the contact |53 to -energize the solenoid coil |5| independently of the switch |55, as previously described. This operation of locking relay |50 independentlyl of the position of the switch |55 is necessary, due to the fact that ina hard landing the switch |55 may .be jarred to the open position, which would render possible the jarring of the throttle to the open position without its being thereafter returned to the closed position. The locking of the solenoid coil of relay |50 is an important feature of the device shown in Figure 7 when employed for the purpose disclosed. Current from the conductor |44 will ow, for example, through contact |26, brush |4|, conductor |66, to contact |65, relay arm |64 of relay |50, conductor |63, through motor armature ||2. Current will return from motor armature 2 through conductor |62, through relay arm |58 of relay |50, to contact |60, conductor |6|, brush |40, contact |24, to the negative power supply conductor |44. The field I of the motor I0 being continuously energized, the current owing through the armature I l2 will cause the motor ||0 to rotate in a direction such that the throttle-control element 4 will be set in the throttle-off position, and the floating lever ||8 will move the switch asand similarly for the glide" and throttle oli" positions the motor |I0 will operate until the contact dead space |28 is opposite contacts |32 andV |34 and contacts |40 and |4| respectively.

While the throttle engine disclosed in Figure 7 has been illustrated as applied to the control of an aircraft engine throttle element, the engine ls also adapted to control other elements-for example, an aircraft or ship rudder. For such use the holding circuit for the relay |50, including relay arm |52 and associated contact |53,v

is eliminated; also the rate-of-climb-responsive control and Vernier adjustment features illustrated in Figure 7 are eliminated. The spacing of the pairs of brushes |40- -|4|, |32|33, and |30-| 3| is so arranged that the middle pair of brushes corresponds to the neutral position ofthe rudder and is equivalent to the operation of the device of Figure 7 in setting the throttle to the cruise position. Then upon energizing either ofthe relays 4or |10, the servomotor ||0 may effect an adjustment of the rudder to either of two angular positions on opposite sides of the neutral position. These positions may be such as to cause predetermined rates of turn in the associated aircraft. v

While AWe have illustrated several preferred embodiments of the invention, it will be apparent to those skilled in the art that other modifications of the invention may\be made, falling within the scope of the invention as dened by the appended claims. y

We claim:

l. In combination an aircraft engine, a throttle control element for said engine, an electric servomotor for actuating said throttle control element into selected predetermined positions, a plurality of switches each selectively operative to energize said servomotor, a plurality of switch means each operative to de-energize said servomotor, a cam follower operatively associated with each of said last named switch means for actuation of the same, a cam associated with each cam follower and actuated by said servomotor, each of said cams being operative to actuate its associated cam follower to thereby de-energize sembly |22 to |26, inclusive, axially to the leftI as seen in Figure 7, to a position such that the brushes 40 and |4| are directly opposite the dead spaces |28, at which time the motor ||0 will be de-energized. Once relay |50 is energized and locked by means of relay arm |52, it will remain energized until the main power supply switch |46 is opened, thus preventing any` accidental opening of the throttle due to jars or jolts in landing, as previously described.

Though the operation of the throttle engine disclosed in Fig. 7 has been described in a certain sequence, by tracing the electrical circuits in the manner as previously described, it will be seen that motor ||0 will always be operated to 4 said servomotor in a respective one of said predetermined positions and means for nely adjusting the relation of one of said cam followers with respect to its associated cam to thereby cause said servomotor to apply a proportional Vernier adjustment to said engine throttle control means.

2. In combination, an aircraft engine, a throttle control element for said engine, an electric servomotor for actuating said throttle control element into selected predetermined positions, a plurality -of switches "each selectively operative to energize said servomotor, a plurality of switch means each operative to de-energize said servo-` motor, a cam follower operatively associated with each of said last named switches for actuation of the same, a cam associated with each cam follower and actuated by said servomotor to thereby de-energize said servomotor in a respective one of said predetermined positions, means for nely adjusting the relation 0f a plurality of said cam followers with respect to their respective associated cams to thereby cause said servomotor to apply a proportional Vernier adjustment to said engine throttle control means in any one of certain of said predetermined positions.

.3. In an electric servomotor of the type having a shaft adapted to be driven a predetermined amount in either direction by a reversible elecpredetermined Value.

tric motor, electric switch means for selectively causing said servomotor to drive said shaft. individual follow-up means each including a cam andoperative to selectively de-energize said electric motor upon said shaft attaining a selected predetermined position, each of said cams being frictionally mounted on said shaft to be driven thereby, locking means cooperating with each of said cams for locking each cam in a predetermined position, means for independently energizing said electric motor to run in either direction relative to a selected locked cam and remotely controlled means for selectively actuating said locking means.

4. The structure as claimed in claim 3, in which the means for locking each of said cams comprises a slot in each cam, a releasable locking detent cooperating with said slot and electrical means for causing said detentto engage said slot.

5. In a control system for regulating certain conditions of ilight of an aircraft such as rate of change of altitude and level flight at"a constant airspeed by regulation oi' the power output of the power plant thereof; comprising regulating means for varying the output of the power plant, servomotor means connected to said regulating means to actuate` the same, selective control means for said servomotor means operative to cause the servomotorfmeans to position the power output regulating means in a selected one of a plurality of predetermined positions each coresponding to a particular value of a respective one of said flight conditions, and separate power operated control means operative when said power output regulating means is positioned in a certain one of said predetermined positions to cause a Vernier adjustment of the power output regulating means in response to variation in the value of the flight condition corresponding to,

said certain position from a predetermined value.

6. 'I'he structure as claimed in claim 5, in which the separate power operated control means includes a. sensitive pressure responsive device responsive to variation in the vertical velocity of the associated airplane as measured in terms y oi rate of change of barometric pressure from a 7. The structure as claimed in claim 5, in which the separate power operated control means includes a sensitive pressure responsive Vdevice responsive to variation in the power plant intake manifold pressure from a predetermined pressure.

8, The structure as claimed in claim 5, in which the separate power operated control means includes a sensitive pressure responsive device responsive to Variation in dynamic pressure of the airstream -from a predetermined value corresponding to a predetermined airspeed.

9. In a control system for regulating certain conditions of night of an aircraft lsuch as rate of change of altitude and level night at a constant airspeed by regulation orthe power output of the' power plant thereof; comprising regulating means for varying the output of the power plant, servomotor means connected to said regulating means to actuate the same, selective control means for said servomotor means operative to cause the servomotor means to position the power output regulating means in a selected one of a plurality of predetermined positions each corresponding to a particular value of a respective one of said iiight conditions, and separate power operated control means for controlling said servomotor means operative when said power output regulating means is in a certain one of said predetermined positions to cause a vernier adjustment of the power output regulating means in response to Variation in the value of the night condition corresponding to said certain position from a predetermined Value.

10. The structure as claimed in claim 9, in which the separate means to control the servomotor means also includes a means operative to cause the servomotor means to apply a Vernier adjustment of the power output regulating means operative when the latter is in another selected one of said predetermined positions than said certain position in response to variation from a predetermined Value of the value of the flight condition corresponding to last named selected position of the power output regulating means.

11. 'I'he structure as claimed in claim 9, in

which the means for applying a Vernier correction to said power output regulating means through said servomotor means includes a. rst control means operative when said power output regulating means is in said certain predetermined position to cause a Vernier adjustment of said power output regulating means in response to Variation in the rate of change of altitude from a predetermined Value and a second control means operative when said power output regulating means is positioned in another one of said predetermined positions to cause a Vernier adjustment of said power output regulating means in response to Variation of the power output of the aircraft power plant from a predetermined value as measured by intake manifold pressure.

12. V'I'lie structure as claimed in claim 9, in which the means for applying a Vernier correction to said power output regulating means through said servomotor means includes a first control means operative when said power output control means is in said certain predetermined position to cause a Vernier adjustment of said power output regulating means in response to variation of the rate of change of altitude from a predetermined Value-and a second control Ameans operative wheny said power output regu- 

